The first thing to understand is ammonia and toxicity. Most of what is said on forums and social media regarding ammonia is simply wrong. I sgould start by saying cycling issue have been a fiocus of my research for the past 15 years. I have run my own bio-farm off and on for at least a decade and I have written several cycling related articles on another large general fish site. What you will see below is from some of those articles.
The first thing to understand is when it cones to aquariums all things are not equal. You and I can have tanks with the exact same Total Ammonia reading and in my tank it will not be a problem but in your it could be killing fish. Gere is why that is the case::
SOME IMPORTANT FACTS ABOUT AMMONIA
Ammonia in water exists in two forms.
NH3, which is the familiar nasty gas we know. Fish exhale NH3. Rotting organic matter will also create ammonia. This stuff is highly toxic and will definitely be harming fish by the time it reaches a concentration of .05 ppm (Some fish and inverts need even lower levels to be safe). However, most of the ammonia in water exists in the form of ammonium which is
NH4. This is way less harmful. But in sufficient concentrations and/or exposure times, it causes external burns. The typical test kits we use measure
Total Ammonia (TA) which is the sum of both NH3 and NH4.
Knowing how dangerous any level of TA might be requires that one know not only how much total ammonia there is but also how much of that total is in each form? The answer depends upon two other water parameters- pH and temperature. The higher the pH and/or temperature, the more of the TA that is in the toxic NH3 form. To calculate how much of the toxic NH3 form of ammonia requires that you know what the
pH and
temperature of your tank water are. Once you know all three numbers (total ammonia, pH and temperature) there is a formula for calculating how much of the total ammonia is in the form of NH3. It is way more complicated to use than most of us can handle. Fortunately, there are charts and tables available for this calculation. There is also currently a handy dandy ammonia calculator you can find here:
http://www.hamzasreef.com/Contents/Calculators/FreeAmmonia.php
1. Choose NH (NH3 + NH4)*
2. Enter in the total ammonia reading from your test, choose ppm.
3. For a fresh water tank, enter 0 for the salinity.
4. Enter your tank’s current pH.
5. Enter your tank temperature and choose F or C, whichever applies.
6. Click Calculate.
The number you want to know is the one for
NH3.
[* If your kit measures ammonia as nitrogen aka –N, choose NH-N (NH3-N + NH4-N) in step 1. above.]
The obvious question re the above is why did I say .05 ppm is the red line for NH3? The answer is that below is what the Merck Veterinary Manual says:
NH3 is highly toxic and frequently limits fish production in intensive systems. It is also dynamic, and when it enters the aquatic system, an equilibrium is established between NH3 and ammonium (NH4+). Of the two, NH3 is far more toxic to fish, and its formation is favored by high pH (>7) and water temperature. When pH exceeds ~8.5, any NH3 present can be dangerous. In general, a normally functioning aquatic system should contain no measurable NH3 because as soon as it enters the system, it should be removed by aerobic bacteria in the environment. Ammonia test kits do not typically measure NH3 directly but instead measure the combination of NH3 and NH4+, referred to as total ammonia nitrogen (TAN). A TAN <1 mg/L is usually not cause for concern unless the pH is >8.5. However, if the amount of NH3 is increased, an explanation should be sought. The amount of toxic NH3 present can be calculated using the TAN, pH, and water temperature. When NH3 levels exceed 0.05 mg/L, damage to gills becomes apparent; levels of 2 mg/L are lethal for many fish. Fish exposed to ammonia may be lethargic and have poor appetites. Acute toxicity may be suggested by neurologic signs such as spinning, disorientation, and convulsions.
ftom
https://www.merckvetmanual.com/exot...nmental-diseases-in-aquatic-systems#v23353508
Why this matters: The nirtifying bacteria reproduce by cell division. This happens when there is more ammonia or nitrite than the bacteria need to thrive. When there is, the bacteria divide. The problem is that they reproduce slowly. Under optimal conditions the ammonia ones need about 8 hours and the nitrite ones about 11. During a cycle, water changes will slow things because lower ammonia or nitrite levels mean less reproduction. One the other hand of these things get to high they will do two things. They will stall a cycle and then they will encourage the wrong strains of bacteria. Different strains are ables to and require specifc concentrations of ammonia or nitrite to thrive. Those in aquariums are adapted to thrive in the lower level found in tanks as opposed to the levels found in waste water.
So how can one deal with ammonia levels that are clearly a threat to fish (remember that depends o NH3 levels moreso than TA levels). There are basically only two thigns we can do. One is chemical and incolves detoxifyif ammonia. This basically converts it all to NH$ for about 24 hours. Mostnitrifying bacteri wants NH3 and is built to use it most efficiently. However, some strains can do well with NH4 and many can use it, but much less efficiently. So using chemicals can help the fish but will also slow the cycling down.
However, plants in tanks use NH4. And they can use it way faster than the bacteria can use NH3. The plants also host the nitrifying bacteria on their roots stems and leaves. The removal of TA can be done by removing only NH3 or NH4. The reason is the balance between them is a function of temp and pH. If the bacteria use some of the NH3 in total ammonia. some of the NH4 will turn back into NH3. Similarly, if the plants use a bunch of NH4, some of the NH3 will turn into NH4. Either way the end result will be undetectable ammonia.
So before you start doing lots of water changes, you need to know howm much of the .25 ppm of TA you are reading is NH3. if the number is Under .05 ppm, do nothing. Of course there is one exception to this. That is the fish themselves. If they are showing sings of ammonia issues, even if the numbers are low, one should still change water. Also, even when Total Ammonia is 100% NH4 (as it will be in tanks approaching pH 6.0 and lower), that ;level is nor harmless at all levels and for all exposure times. For the short term of a cycle where there are fish my rule of thumb is 2 ppm of TA is the maximum one should allow to exist for any length of time. A day or two may be OK but not much more.
SIGNS OF AMMONIA POISONING
Fish will not behave as they normally do. Signs of ammonia poisoning can include sluggish behavior, panting, and gill discoloration (gill burn). Fish may hang just below the water surface or they may hide or stop eating. When you know you have ammonia in the tank during cycling and you notice such behavioral changes, the best course of action, regardless of test results, it to do an immediate water change of 50% or more.
The next thing to consider is nitrite. This killls fish by suffocating them. But it does this inside the fish.
“Nitrite enters the bloodstream through the gills and turns the blood to a chocolate-brown color. Hemoglobin, which transports oxygen in the blood, combines with nitrite to form methemoglobin, which is incapable of oxygen transport. Brown blood cannot carry sufficient amounts of oxygen, and affected fish can suffocate despite adequate oxygen concentration in the water. This accounts for the gasping behavior often observed in fish with brown blood disease, even when oxygen levels are relatively high.”
from
https://srac.tamu.edu/fact-sheets/serve/110
Again quoting myself from one of y articles:
SIGNS OF NITRITE POISONING
Fish will not behave as they normally do. Because their blood is not carrying oxygen, fish will behave as if they are suffocating. They may hang just below the water surface or near filter outflows trying to get air. What you will not see is any outward sign of bodily damage nor damage to the gills of the fish. However, you should see gills changing color to a brownish rather than their normal coloration.
HOW TO MANAGE NITRITE POISONING
Fortunately, there is an effective way to blunt the harmful effects of elevated nitrite that doesn’t involve changing lots of water- you add salt (sodium chloride) to the water. The
chloride in the salt acts to ” block” the ability of nitrite to enter though the gills of the fish and thus to cause the harm inside the fish it might. So it is possible to manage elevated nitrite over the short term using salt in relatively small amounts.
“Sodium chloride (common salt, NaCl) is used to “treat” brown blood disease. Calcium chloride can also be used but is typically more expensive. The chloride portion of salt competes with nitrite for absorption through the gills. Maintaining at least a 10 to 1 ratio of chloride to nitrite in a pond effectively prevents nitrite from entering catfish.” 1
It should be noted that the Merck Veterinary manual suggests a lower ratio of chloride: " The concentration of Cl needed (mg/L) = (6 × NO2) − Cl present. " (from the same link to Merck as for ammonia above.)
Since the amount of salt needed to produce either 6 or 10 times the chloride as nitrite is minimal, this author prefers to use the higher ratio of 10 to 1 in order to be more certain of obtaining the needed relief. One should also be aware that studies indicate that, whether one changes water or uses chloride to counter the effects of nitrite toxicity, it will still take between 24-72 hours for nitrite already inside fish to be completely eliminated. Preventing further nitrite from entering usually solves the problem.
The methodology for dealing with nitrite is a longish explanation. It may require diluted testing for nitrite. For this one needs some pure water (either distilled or RO/DI) It also requires several math steps (using basic math only) to arrive at the amount of salt needed to combat any given level of nitrite. Since the OP reports 0 nitrite, I will not include it here. However, the amount of salt to add depends upon actual nitrite levels and the actual volume of water in a tank. The one things Ican say is that the level of salt is actually so low that even salt sensitive fish can handle it for the short time nitrite should be present.
Finally, I am happy to offer this site my articles, I made the same offer on AquariaCentral and it was met with silence. I expect the same will be the case here. For members interested, they are on a competeing site. So I will not post the links in this forum. However, If anybody wants to read them, you can send me a PM and I will PM the link to you. I have not been active on that site since shortly after my three cycling related articles were posted in July 2014. They are still on that site today. As far as I can tell, there are no cycling articles on this site?
I tested again, ammonia was .25, nitrite was .5, and I did not test nitrate.
